The invention relates to blood bags having an interconnecting system.
Blood bags serve for the taking, storage, preparation and transfusion of blood and blood components. One of the advantages of blood bags over blood bottles of glass is that with multiple blood bag systems blood preparations can be made in a closed, i.e., sterile system. The making of blood preparations is gaining importance in connection with "customized hemotherapy."
Multiple bag systems as available on the market at the present time consist of two or more bag systems in which generally a primary bag contains the blood stabilizer solution and serves for receiving the blood. The secondary or satellite bag, or the satellite bag system which is connected by a system of tubing to the primary bag, serves for the preparation of the blood components such as plasma, factor VIII concentrate, thrombocyte concentrate, etc.
To prevent the solution or blood in the primary bag from passing into the tubing system of the secondary bag system before preparation, the primary bag has a system for interconnection, which, when opened, permits the preparation to pass over from the primary bag to the secondary bag.
For this interconnection system a variety of possibilities exist.
For example, an interconnection system is known which consists of a ball forced into flexible tubing. Free passage is permitted when the ball is squeezed out of the tubing. This system has the disadvantage that, under extreme conditions, such as overpressure, centrifugation, mechanical changes in tubing diameter, etc., the seal is not hermetic.
Systems are furthermore known which utilize clamping means, but they usually have the disadvantage that they are bulky, and that the inserted tube is permanently narrowed or stuck shut before the bag is used, so that when the clamp is opened flow through the tube is constricted.
U.S. Pat. No. 3,110,308 describes a connecting system utilizing a membrane whch is perforated by a cannula-like needle. In this system, the complicated and time-consuming handling is often the subject of complaints.
Lastly, break-off systems are known, in which free passage is made possible by breaking off a plastic piece in a tubing system. Such systems are situated outside of a blood bag in the flexible tubing connecting the primary and secondary bags. This has the disadvantage that often it is impossible to achieve a clean and optimum separation of the blood preparations, after centrifugation for example, and the preparation becomes contaminated. Furthermore, the manufacture and assembly of such systems is complicated and costly.